body {
	background: url(img/banner4.jpg) fixed;
	background-size: cover;
	background-repeat: no-repeat;
	margin: auto;
}

* {
	margin: 0;
	padding: 0;
	list-style: none;
	text-decoration: none;
}

.banner {
	height: 500px;
}

.banner1 {
	background-image: url(img/banner.jpg);
}

.banner2 {
	background-image: url(img/banner2.jpg);
}

.banner3 {
	background-image: url(img/banner3.jpg);
}

@media (max-width:600px) {
	.banner {
		height: 230px;
		background-size: 100% 300px;
		background-repeat: no-repeat;
	}
}

.card .card-text {
	height: 30px;
/*	理解仅仅局限于隐藏溢出*/
	overflow: hidden;
/*	属性规定当文本溢出包含元素时发生的事情*/
	text-overflow: ellipsis;
/*	规定段落中的文本不进行换行*/
	white-space: nowrap;
}


footer {
	background: white;
}
footer a{
	font-size: 14px;
}
